I have a young friend who set up a tank for her 10 year old son. Basically the tank is doing well except that in the last 3 months of so the snail shells have been disintegrating. Originally I gave her ramshorns and she was able to share with others. Then she called me and said could I give her more snails, so I sent 60 -70 MTS to her 2 weeks ago. Last night she tells me that most of them have died and the shells are uravelling.And so they are-- the pointed ends have come undone and they are all ragged.
She lives in the north end of town and I live in the mid section. Recently, in August the town changed from chloramine to free chlorine to purify the water pipes in her section of town. Ours was changed at the beginning of november.
In the last year my ph has dropped from 8.3- 7.2 as my section of town is now getting water sent from lake ontario mixed with local artesian well water.
Can anyone tell me if the change in chloramine to free chlorine would be a problem?
Is it that the water is softer?
Could it be that her tank is reacting to something more local to her neighbourhood?
Her tank is the standard kids tank- right colored stones, a few ornaments and some plants I gave them.

Any ideas what has gone wrong?? She did try to use a ph raiser but she had an aweful mess in her tank with precipitate. Lucky she didn`t lose the whole mess.

I agree, It sounds like a issue with the amount of Calcium in the water. Low Calcium usually is not a issue for us humans. Typically we prefer low Calcium in water around the home, It reduces spots on dishes, makes washed clothes brighter, among many other things. But for pets it can cause issues like you described, or soft eggs in breeding birds, or even bone issues in cats and dogs. We humans typically supplement it in our diets without even knowing it. As stated place a few eggshell flakes in the tank or part of a cuttle bone you could buy from the bird section at a petstore should do the trick.
Oh never mind, I didn't need to post - Just do what emc said.

The difference in chlorine isn't ther problem, but it does show that there is a big difference in the water chemistries of the two areas. Her water is obviously much softer than yours. It takes both calcium and magnesium to grow snail shells, so don't just add calcium, add magnesium. Any magnesium supplement for aquariums would be fine, or even a heaping tablespoon of epsom salts. It only takes a little magnesium compared to calcium, exactly half as much, actually.